Davidbfo,

Firn no doubt knows far more, but many ex-colonies have very little non-natural resources to trade with us. Oil and gas is the exception, which affected the UK's stance on Biafra's attempt to secede from Nigeria (France covertly took a different stance).
US policy is Africa is to follow the lead of the ex-colonial power (e.g Congo with the Belgians who had Lumumba killed, Francophone Africa presently) or just stay neutral (e.g. Biafra and the British).

In this the best stance to take in a Post-Cold War World, in a World where the presence of China creates facts on the ground, complicating relationships?

I don't know.